U.S. patent number 5,626,534 [Application Number 08/525,687] was granted by the patent office on 1997-05-06 for clutch control system.
This patent grant is currently assigned to Automotive Products, plc. Invention is credited to Jonathan D. Ashley, Charles J. Jones.
United States Patent |
5,626,534 |
Ashley , et al. |
May 6, 1997 |
Clutch control system
Abstract
A clutch control system for the automatic control of a motor
vehicle clutch which connects an engine with a gearbox under the
control of a driver-operated gear ratio selector lever. The control
system includes an electronic control unit which controls initial
clutch take-up on starting of the vehicle, clutch re-engagment
following each ratio change, clutch disengagment on movement of the
gear selector lever to change the operative ratio of the gearbox,
and clutch disengagment on the coming to rest, etc. of the vehicle.
The control system also incorporates an automatic calibration
routine which is invoked on the inital keying-on of the system,
said routine comprising a predetermined sequence of events in which
the system responds to actions of the operator and at predetermined
that the system is ready to proceed to the next stage of the
calibration.
Inventors: |
Ashley; Jonathan D. (Solihull,
GB), Jones; Charles J. (Coventry, GB) |
Assignee: |
Automotive Products, plc
(Leamington Spa, GB)
|
Family
ID: |
10749952 |
Appl.
No.: |
08/525,687 |
Filed: |
September 29, 1995 |
PCT
Filed: |
February 06, 1995 |
PCT No.: |
PCT/GB95/00236 |
371
Date: |
September 29, 1995 |
102(e)
Date: |
September 29, 1995 |
PCT
Pub. No.: |
WO95/21073 |
PCT
Pub. Date: |
August 10, 1995 |
Foreign Application Priority Data
|
|
|
|
|
Feb 5, 1994 [GB] |
|
|
94 02252 |
|
Current U.S.
Class: |
477/79;
477/86 |
Current CPC
Class: |
B60W
10/02 (20130101); F16D 48/06 (20130101); B60W
10/06 (20130101); B60W 30/18 (20130101); B60W
10/11 (20130101); B60W 10/10 (20130101); F16H
59/044 (20130101); B60W 30/1819 (20130101); F16H
59/70 (20130101); F16H 2342/02 (20130101); F16H
2342/04 (20130101); F16D 2500/7104 (20130101); F16H
2061/064 (20130101); F16D 2500/3069 (20130101); F16D
2500/3108 (20130101); F16H 2061/283 (20130101); F16D
2500/3067 (20130101); F16D 2500/50263 (20130101); F16D
2500/30408 (20130101); F16D 2500/31466 (20130101); F16D
2500/31426 (20130101); F16D 2500/5026 (20130101); F16H
2061/0087 (20130101); F16H 63/46 (20130101); F16D
2500/5018 (20130101); F16D 2500/7103 (20130101) |
Current International
Class: |
F16H
59/70 (20060101); F16D 48/06 (20060101); F16D
48/00 (20060101); F16H 59/04 (20060101); F16H
61/00 (20060101); F16H 63/46 (20060101); F16H
63/00 (20060101); B60K 041/22 (); F16H 059/02 ();
F16H 059/04 (); F16H 059/70 () |
Field of
Search: |
;477/70,79,86 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
243022 |
|
Oct 1987 |
|
EP |
|
3313803 |
|
Nov 1983 |
|
DE |
|
59-097325 |
|
Jun 1984 |
|
JP |
|
2058963 |
|
Apr 1981 |
|
GB |
|
92-13208 |
|
Aug 1992 |
|
WO |
|
Other References
"Automotive Engineering" vol. 101, No. 9, Sep. 1993 p. 70..
|
Primary Examiner: Wright; Dirk
Attorney, Agent or Firm: Milliken; Paul E. Germain; Lee
A.
Claims
We claim:
1. A clutch control system for the automatic control of a motor
vehicle clutch which connects an engine with a gearbox under the
control of a driver-operated gear ratio selector lever, the control
system comprising an electronic control unit which controls initial
clutch take-up on starting of the vehicle, clutch re-engagement
following each ratio change, clutch disengagement on movement of
the gear selector lever to change the operative ratio of the
gearbox, and clutch disengagement on the coming to rest of the
vehicle, the control unit including an automatic calibration
routine which is invoked on the initial keying-on of the system,
said routine comprising a predetermined sequence of events (A to U)
in which the system responds to actions (B,L,P3,R3) of an operator
of the vehicle and at predetermined points (K,N,P11,T) in the
calibration routine advises the operator that the system is ready
to proceed to the next stage of the calibration.
2. A control system according to claim 1 wherein the calibration
routine includes the measurement and saving to memory of signals
representative of at least one of the following parameters:
location (E) of a permissible neutral range of the gear selector
lever (24);
position of an associated vehicle throttle (16) in a foot-off
condition (F);
position of an associated vehicle throttle (16) in a fully
depressed foot-on condition (M);
position of the clutch (14) in its engaged clamped condition
(G);
solenoid valve current (I) corresponding to a null position of a
solenoid valve which controls the supply of fluid to and exhaust of
fluid from an associated clutch actuator (22), and
location (P,R) relative to the permissible neutral range (E) of a
permissible range of gear selector lever positions for each ratio
of the gearbox (12).
3. A control system according to claim 2 wherein calibration (E) of
the location of the neutral range of positions of the gear selector
lever (24) and the foot-off throttle position (F) takes place in
parallel with calibration (G) of the clutch clamped position and
the null-position solenoid valve current (I), and in that after
checking (J) that all these calibrations have been successfully
completed, the calibration routine issues a first operator advice
signal (K).
4. A control system according to claim 3 wherein the first and all
subsequent operator advice signals (K,N,P11,T) comprise the
sounding of an audible warning (50) and/or the activation of a
visible warning.
5. A clutch control system according to claim 4 wherein the
calibration (E) of the neutral range of the gear selector lever is
obtained by the operator moving the lever (24) to a neutral
position, the system checking that no selecting force is currently
being applied to the gear selector lever thus confirming that the
operator has placed the lever in the intended neutral position, and
the system then measuring and saving to memory a signal
representative of a neutral plane position and ascribing a
permissible future range (f) of neutral selection positions based
on the measured neutral position.
6. A control system according to claim 2 wherein the foot-off
throttle calibration (F) is achieved by the system recording the
signal corresponding to a fully released throttle (16).
7. A control system according to claim 2 wherein the clutch clamped
position is calibrated (G) by measuring and recording a signal from
the clutch actuator (22) corresponding to the fully engaged
condition of the clutch (14).
8. A control system according to claim 2 wherein the null-position
solenoid valve current is calibrated (I) by measuring and recording
the solenoid current with the clutch (14) fully disengaged and the
solenoid valve in its null position.
9. A control system according to claim 8 wherein the calibration
routine includes the step (H) of issuing a command to disengage the
clutch (14) whilst the null-position current is read and recorded
(I).
10. A control system according to claim 3 wherein following the
first operator advice signal (k) the routine enters a foot-on
throttle calibration stage (M) in which the operator is required
(L) to fully depress the throttle pedal (19) to enable the control
unit (36) to record a signal corresponding to the fully depressed
foot-on throttle position, a second operator advice signal (N)
being issued by the system after the foot-on throttle signal is
recorded indicating that the routine is ready to begin the
calibration (P) of the permissible range of gear selector lever
positions for each ratio of the gearbox (12).
11. A control system according to claim 10 wherein an engine
starting circuit is enabled (O) after the second operator advice
signal (N).
12. A control system according to claim 2 wherein calibration (P)
of the permissible range of gear lever positions for each forward
ratio of the gearbox is achieved using the following routine:
the system checks (P1) that the gear selector lever is in the
permissible neutral range;
the system detects (P4) whether a push or pull load is being
applied to the selector lever 24 by the operator to determine to
which side of the neutral plane the selector lever has been
moved;
the system checks (P5) that the gear lever (24) has entered a
permitted range of lever positions for the gear in question and
starts (P6) a timed delay;
the system detects (P7) a signal corresponding to the extremity of
movement of the gear lever (24) into the particular gear selection
position at the end of the timed delay;
the system compares (P9) current engine and vehicle speeds to
determine which gear ratio is currently selected in the
gearbox;
the system checks (P10) the compatibility of the determined gear
ratio with the gear lever load signal; the system ascribes (P10) a
permissible range of lever positions, based on the detected
extremity of movement of the gear lever (24), to the gear in
question in the system memory, and
the system issues an operator advice signal (P11) to indicate that
the calibration of that particular gear lever position range is
completed and that the system is ready to calibrate any remaining
gear lever position ranges.
13. A control system according to claim 12 wherein after the
issuance of the operator advice signal (P11) indicating completion
of the calibration range for the last forward ratio the routine
enters a checking stage (Q) in which the system checks that it has
saved valid signals corresponding to a permissible range of gear
lever positions for each forward ratio of the gearbox (12) and that
the vehicle speed has exceeded a predetermined level.
14. A control system according to claim 13, wherein calibration (R)
of the range of permissible gear selector lever positions for
reverse gear selection is made using the following routine for the
calibration of the forward ratio positions:
the system checks (P1) that the gear selector lever is in the
permissible range;
the system detects (P4) whether a push or pull load is being
applied to the selector lever 24 by the operator to determine to
which side of the neutral plane the selector lever has been
moved;
the system check (P5) that the gear lever (24) has entered a
permitted range of lever positions for the gear in question and
starts (P6) a timed delay;
the system detects (P7) a signal corresponding to the extremity of
movement of the gear lever (24) into the particular gear selection
position at the end of the timed delay;
the system checks (P10) the compatibility of the determined gear
ratio with the gear lever load signal;
the system ascribes (P10) a permissible range of lever positions,
based on the detected extremity of movement of the gear lever (24),
to the gear in question in the system memory, and
the system issues an operator advice signal (P11) to indicate that
the calibration of the particular gear lever position range is
completed and that the system is ready to calibrate any remaining
gear lever position ranges.
15. A control system according to claim 14 wherein the operator
advice signal (T) issued after the completion of the calibration of
the range of permissible gear selector lever positions for reverse
gear selection indicates the completion of the entire system
calibration routine.
16. A method of calibrating a clutch control system for the
automatic control of a motor vehicle clutch which connects an
engine with a gearbox under the control of a driver-operated gear
ratio selector lever, the control system comprising an electronic
control unit which controls initial clutch take-up on starting of
the vehicle, clutch re-engagement following each ratio change,
clutch disengagement on movement of the gear selector lever to
change the operative ratio of the gearbox, and clutch disengagement
on the coming to rest of the vehicle, comprising the step of keying
on the system thus invoking an automatic calibration routine stored
in the control unit in which the system responds to the actions of
the operator and at predetermined points in the calibration routine
advises an operator of the vehicle that the system is ready to
proceed to a next stage of the calibration.
17. A method of calibrating each forward gear selector lever
position of a clutch control system for the automatic control of a
motor vehicle clutch which connects an engine with a gearbox under
the control of a driver-operated gear ratio selector lever, the
control system comprising an electronic control unit which controls
initial clutch take-up on starting of the vehicle, clutch
re-engagement following each ratio change, clutch disengagement on
movement of the gear selector lever to change the operative ratio
of the gearbox, and clutch disengagement on the coming to rest of
the vehicle, comprising the step of moving the gear selector lever
from a neutral plane to each gear selector position in turn and
while in or moving towards each position performing the steps
of:
detecting whether a push or pull load is being applied to the
selector lever by an operator of the vehicle to determine to which
side of the neutral plane the selector lever has been moved;
checking that the selector lever has entered a permitted range of
lever positions for the gear in question and starting a timed delay
on entry into said range;
detecting a signal corresponding to the extremity of movement of
the gear selector lever into a particular gear selection
position;
comparing current engine and vehicle speeds to determine which
ratio is selected in the gearbox;
checking for compatibility of a determined gear ratio with the
lever load signal;
ascribing a permissible range of lever positions, based on the
detected extremity of movement of the gear lever to the gear in
question in system memory, and
issuing an operator advice signal that calibration of that
particular gear lever position is complete and that any remaining
gear lever position may now be calibrated using the same
procedure.
18. The method of claim 17 wherein the control unit incorporates an
automatic calibration routine for carrying out the gear lever
position calibration.
Description
This invention relates to a clutch control system for the automatic
control of a motor vehicle clutch which connects an engine with a
gearbox under the control of a driver-operated gear ratio selector
lever, the control system including an electronic control unit
which controls initial clutch take-up on starting of the vehicle,
clutch re-engagement following each ratio change, clutch
disengagement on movement of the gear selector lever to change the
operative ratio of the gearbox, and clutch disengagement on the
coming to rest etc of the vehicle. Such a clutch control system is
herein after referred to as a clutch control system of the kind
specified.
Examples of such systems are described in the Applicants earlier
European patents nos. 0038113, 0043660, 0059035 and 0101220 and
European Application No. 0566595.
After assembly a clutch control system of the kind specified
requires calibration before it can operate. Such calibration can
prove to be a time consuming process which is difficult to
incorporate into a vehicle assembly line manufacturing
procedure.
It is an object of the present invention to provide a clutch
control system of the kind specified which overcomes the above
calibration problem.
Thus according to the present invention there is provided a clutch
control system of the kind specified characterised in that the
control unit incorporates an automatic calibration routine which is
invoked on the initial keying-on of the system, said routine
comprising a predetermined sequence of events in which the system
responds to actions of the operator and at predetermined points in
the calibration routine advises the operator that the system is
ready to proceed to the next stage of the calibration.
In a typical clutch control system of the kind specified the clutch
is spring engaged (eg by a diaphragm spring) and is disengaged by
an hydraulic or other fluid pressure operated actuator the supply
of fluid to, and exhaust of fluid from, which is controlled by the
control unit via a solenoid-operated fluid flow control valve
having a null position in which flow of fluid to and exhaust of
fluid from the actuator is shut-off. The control unit also receives
signals indicative of the position of an associated throttle, the
state of engagement of the clutch, vehicle engine speed, vehicle
speed, gearbox ratio currently selected, and loading (eg push or
pull loading) on the gear selector lever.
When applying the present invention to such a clutch control system
the calibration routine typically includes the measurement and
saving to memory of signals representative of the following
parameters:
location of the permissible neutral range of the gear selector
lever;
position of the throttle in a foot-off condition;
position of the throttle in a foot-on condition;
position of the clutch in its engaged clamped condition;
solenoid valve current corresponding to a null position of a
solenoid valve which controls the supply of fluid to and exhaust of
fluid from an associated clutch actuator, and
location relative to the permissible neutral range of a permissible
range of gear selector lever positions for each ratio of the
gearbox.
In a preferred arrangement calibration of the neutral range of
positions of the selector lever and the foot-off throttle position
takes place in parallel with calibration of the clutch clamped
position and the null-position solenoid valve current, and after
checking that all these calibrations have been sucessfully
completed, the calibration routine issues a first operator advice
signal.
Preferably the first and all subsequent operator advice signals
comprise the sounding of an audible warning (eg a buzzer) and/or
the activation of a visible warning (eg a flashing indicator
light).
The calibration of the neutral range of the gear selector lever is
obtained by the operator moving the lever to a neutral position,
the system checking that no selecting force is currently being
applied to the gear selector lever thus confirming that the
opearator has placed the lever in the intended neutral position,
and the system then measuring and saving to memory a signal
representative of a neutral plane position and ascribing a
permissable future range of neutral selection positions based on
the measured neutral position.
The foot-off throttle calibration is achieved by the system simply
recording the signal corresponding to a fully released
throttle.
The clutch clamped position is calibrated by measuring and
recording a signal from the clutch actuator corresponding to the
fully engaged condition of the clutch.
The null-position current is calibrated by measuring and recording
the solenoid current with the clutch fully disengaged and the
solenoid valve in its null-position.
Preferably the calibration routine includes the step of issuing a
command to disengage the clutch whilst the null-position current is
read and recorded.
Following the first operator advice signal the routine enters the
foot-on throttle calibration stage in which the operator is
required to fully depresses the throttle pedal to enable the
control unit to record a signal corresponding to the fully
depressed throttle position. After the system has recorded the
foot-on throttle signal the buzzer and/or warning light is again
activated to provide a second operator advice signal indicating
that the routine is ready to begin the calibration of gear
selection positions. The engine starter starting circuit is also
enabled after the second operator advice signal.
The calibration of the selector lever positions corresponding to
each forward ratio can be carried out with the vehicle either being
driven over the ground or on a rolling road. This calibration can
be achieved using the following routine:
the system checks that the gear selector lever is in the
permissible neutral range;
the system detects whether a push or pull load is being applied to
the selector lever by the operator to determine to which side of
the neutral plane the selector lever has been moved;
the system checks that the gear lever has entered a permitted range
of lever positions for the gear in question and starts a timed
delay;
the system detects a signal corresponding to the extremity of
movement of the gear lever into the particular gear selection
position at the end of the timed delay;
the system compares the current engine and vehicle speeds to
determine which gear is selected in the gearbox;
the system checks the compatibility of the determined gear ratio
with the gear lever load signal;
the system ascribes a permissible range of lever positions, based
on the detected extremity of movement of the gear lever, to the
gear in question in the system memory, and
the system issues an operator advice signal (using the buzzer) that
the calibration of that particular gear lever position is complete
and that the system is ready to calibrate any remaining gear lever
positions.
When the buzzer has sounded indicating the completion of the last
forward gear lever position calibration, the calibration routine
preferably enters a checking stage in which the system checks that
it has saved valid signals corresponding to a permissible range of
gear lever positions for each forward ratio of the gearbox and that
the vehicle speed has exceeded a predetermined level (eg 60 Kph).
If both these criteria are met the forward gear lever position
calibration is complete and a further operator advice signal is
issued.
The final stage in the calibration is the calibration of the range
of permissible gear lever positions for reverse gear selection.
This calibration is undertaken in the same manner as the
calibration for each of the forward ratios with the exception that
the engine and vehicle speed comparison is not made since the
reverse selection can be calibrated with the vehicle at rest.
Following completion of the calibration of the reverse gear
position a final buzzer is sounded indicating total completion of
the entire calibration routine.
In accordance with a further aspect of the present invention there
is provided a method of calibrating a clutch control system of the
kind specified comprising keying-on the system thus invoking an
automatic calibration routine stored in the control unit in which
the system responds to the actions of the operator and at
predetermined points in the calibration routine advises the
operator that the system is ready to proceed to the next stage of
the calibration.
The invention also provides a method of calibrating each of the
forward gear selector lever positions of a clutch control system of
the kind specified comprising moving the gear selector lever from
neutral to each gear selector position in turn and whilst in or
moving towards each position:
detecting whether a push or pull load is being applied to the
selector lever by the operator to determine to which side of the
selector lever neutral plane the selector lever has been moved;
checking that the selector lever has entered a permitted range of
lever positions for the gear in question and starting a timed delay
on entry into said range;
detecting a signal corresponding to the extremity of movement of
the gear lever into the particular gear selection position;
comparing the current engine and vehicle speeds to determine which
ratio is selected in the gearbox;
checking for compatibility of the determined gear ratio with the
lever load signal;
ascribing a permissible range of lever positions, based on the
detected extremity of movement of the gear lever to the gear in
question in system memory, and issuing an operator advice signal
that calibration of that particular gear lever position is complete
and that any remaining gear lever position may now be calibrated
using the same procedure.
The invention also provides a clutch control system of the kind
specified in which the control unit incorporates an automatic
calibration routine for carrying out the above method of
calibrating each of the gear lever positions.
The present invention will now be described, by way of example
only, with reference to the accompanying drawings in which:
FIG. 1 shows in diagrammatic form the general layout of a clutch
control system of the kind specified embodying the present
invention;
FIG. 2 shows in flow diagram form the main steps in the calibration
routine of the present invention;
FIG. 3 shows in flow diagram form the details of the calibration of
the gear selector lever positions, and
FIG. 4 shows the permissable selection ranges ascribed to each
gearbox ratio.
Referring to FIG. 1 this shows an engine 10 with a starter and an
associated starter circuit 10a which is coupled through a friction
clutch 14 with a gearbox 12 via a gearbox input shaft 15. In the
example described, fuel is supplied to the engine by a throttle 16
which includes a throttle valve 18 operated by accelerator pedal
19. The invention is equally applicable to electronic or mechanical
fuel injected petrol or diesel engines.
The clutch 14 is actuated by a release fork 20 which is operated by
a slave cylinder 22. The gearbox is controlled by a gear ratio
selector lever 24 which is connected with the gearbox via a
selector linkage 25 and which includes a load-sensing switch means
33 which detects forces applied to the lever 24 by the driver and
produces a signal Vs indicating an intention to change gear.
An electronic control unit 36 controls the actuation of the clutch
14 via an hydraulic control 38 which controls the operation of
slave cylinder 22. Control unit 36 receives signals Vs from gear
lever 24 and signals Ve proportional to engine speed from engine
speed sensor 26. Signals Vt from throttle valve position sensor 30
proportional to the current throttle opening and accelerator pedal
postion signals Va from an accelerator positon sensor 19a are also
fed to control unit 36. Control unit 36 also receives a gear signal
Vg from gear position sensor 32 which corresponds to the gear ratio
currently engaged, signals Vc from slave cylinder position sensor
34, which varying with the position of the slave cylinder, and
signals Vdp proportional to clutch driven plate speed from speed
sensor 42 which actually senses the speed of the gearbox input
shaft 15 (which is equal to that of a driven plate 40 of the clutch
14). Since the speed of the vehicle depends on the driven plate
speed and the gear engaged, the driven plate speed sensor 42 acts
in effect as a vehicle speed sensor and vice versa. Thus in some
applications no driven plate speed sensor 42 is provided and this
speed is calculated from the gearbox ratio and the vehicle speed
which is given by a vehicle speed sensor (not shown) of, for
example, the variable reluctance type.
A throttle control 37 is operated by the control unit 36 so that
the throttle can be opened and closed independently of the
accelerator pedal 19.
A buzzer 50 is connected with control unit 36 to warn/indicate to
the vehicle operator when certain vehicle operating conditions
occur. In addition to or in place of buzzer 50 a flashing warning
light (not shown) may be used.
Control unit 36 includes a reference signal generator which
generates a reference signal Vr representative of a desired engine
speed. This reference signal is compared with the actual engine
speed signal Ve to produce an error signal E which is compared with
the clutch actuator position signal Vc to provide a clutch
engagement control signal Vce which control unit 36 outputs to
hydraulic control 38. Operation of a control unit in this manner is
described in more detail, for example, in the Applicants earlier
European Patents 0038113 and 0043660. Since the general details of
the control logic of the control unit 36 do not form part of the
present invention further details will not be given here but the
reader is directed to the Applicants various earlier patents and
pending application referred to above if further details are
required.
In addition to controlling the engagement and disengagement of
clutch 14 the control unit 36 also controls the throttle setting
via control 37 when its control logic indicates that an overide of
the throttle opening set by the driver's operation of the
accelerator 19 is desirable. In some applications the throttle
control 37 may be omitted.
In accordance with the present invention the control unit 36
incorporates, in non-volatile memory, an automatic calibration
routine (illustrated in flow diagram form in FIG. 2) which is
invoked on the initial keying on of the system.
During the later stages of the manufacture of the control unit 36
when all the initial control parameter values are written into the
unit's non-volatile memory all the calibration flags are cleared.
There is a calibration flag for each stage of the calibration this
flag is set when that stage of the calibration has been
successfully completed. There is also a master flag the so-called
"end of the line flag" (E.O.L. Flag) which is set when the entire
calibration routine is complete.
Thus on initial keying-on of the system (see block A in FIG. 2) the
E.O.L. flag is clear indicating that the end of line calibration
routine is to be undertaken.
The calibration routine illustrated in FIG. 2 is set in motion by
the vehicle operator placing the gear lever 24 in neutral (see
action block B of FIG. 2).
When the gear lever is placed in neutral the software will detect
entry into a pre-programmed allowable neutral band or range and
check that the gear lever 24 is unloaded by reading the output from
load sensing switch means 33 (see block C of FIG. 2). A 0.5 sec
timer is then started (see block D of FIG. 2) and at the end of
this delay the currently occupied gear lever position will be taken
as the "neutral position". The boundaries of the permissable future
neutral range are determined by the system from this neutral
position and the neutral calibrated flag set (see block E of FIG.
2). The remaining gear positions are later referenced with respect
to this neutral position.
If the permissable neutral range determined by the system is within
predetermined limits the calibration of the foot off-throttle
position is undertaken (see block F of FIG. 2) by recording the
foot-off reading from accelerator pedal sensor 19a.
As can be seen from FIG. 2 at the same time that blocks C to F of
the calibration are in progress the calibration of the clutch clamp
position and the hydraulic control unit 38 is also taking place via
block G to I.
Hydraulic control 38 comprises a powerpack (not shown) which
includes an electric motor-driven hydraulic pump which is
powered-up on keying-on of the system and an accumulator which
delivers pressured hydraulic fluid to slave cylinder 22 via a
solenoid-operated fluid flow control valve (also not shown).
Details of a suitable powerpack are contained in the Applicant's
earlier European Patent No. 0430943.
At block G the clutch clamped position is calibrated by recording
to non-volatile memory a signal from sensor 34 representing the
clamped position of the clutch.
The hydraulic control 38 is calibrated by saving to non-volatile
memory a signal representing the steady current which must be
applied to the solenoid of the fluid flow control valve to obtain
the null-position of the valve when the clutch is fully disengaged
with the pump not running to ensure a steady state condition.
This null-current must be read when the clutch is disengaged (as
opposed to engaged) since this is the condition in which the clutch
cylinder 22 is fully in control of the state of engagement of the
clutch.
To obtain this current signal the system is set up so that the
calibration routine itself includes the step of issuing a clutch
disengage signal to the hydraulic control 38 (see block H of FIG.
2). The null-position current is then read into non-volatile memory
(see block I of FIG. 2).
The sucessful completion of steps C to F and G to I of the
calibration is checked (see block J of FIG. 2) by checking that
acceptable values representative of the neutral range,
throttle-off, clutch clamped position and null-current have all
been saved to memory. If so, the buzzer is sounded (see block K of
FIG. 2) to indicate sucessful completion of blocks C to I of the
calibration. If no buzzer is sounded at this point, indicating a
calibration problem, it is necessary for the operator to determine,
using an electronic diagnostic tool plugged into the control unit,
where the problem lies and to correct this problem before
attempting to re-calibrate whichever step of the calibration has
previously failed. (see block X of FIG. 2).
Following the successful obtaining of a buzzer at step K, the
operator fully depresses the accelerator pedal 19 (see action block
L of FIG. 2) so that the calibration of the foot-on throttle can
take place (see block M of FIG. 2) during which a first snapshot of
the foot-on throttle position is taken and saved to memory. In
fact, the foot-on throttle position is monitored until the entire
calibration routine is complete and if any foot-on value is
recorded which is higher than the initial snapshot this higher
value becomes the saved value.
After the saving of the snapshot of foot-on throttle position to
memory the buzzer is sounded (see block N of FIG. 2) to indicate to
the operator the completion of the static section of the
calibration which is done with the vehicle stationary and the
stater circuit 10a is enabled (see block O of FIG. 2) to allow
starting of the engine.
If necessary the calibration can be halted at this point and the
calibrations achieved will not be lost if the system is keyed-off.
On the next keying-on the calibration routine would pick up at this
point with the stater circuit enabled.
The sounding of the buzzer at block N indicates the start of the
calibration process for the forward gears (see block P of FIG. 2).
This can take place as the vehicle is driven off the production
line from rest and up through the gears or on a rolling road which
forms part of the production line. The calibration procedure for
each of the forward gears (shown in more detail in FIG. 3 which
expands the block P of FIG. 2) is the same for each gear and is
based on the following principles.
The process for each gear is started by checking that the gear
lever is in the previous prescribed neutral range (see block P1 of
FIG. 3). When this position is detected for the first time any
existing gear lever positions or range values are reset so that the
system is ready to receive the new calibration values. As the gear
selector lever 24 is moved to each gear selection position in turn
(see action block P3 of FIG. 3) the gear lever is monitored to see
if it is being pushed or pulled (see block P4 of FIG. 3). Neutral
is arranged to be close to the mid travel of the transducer with
the positions for the gears on either side of neutral (see FIG.
4).
Thus, depending on the direction of travel of the gear selector
lever the transducer from neutral, a maximum or minimum output from
the gear transducer 32 is sought as each gear is selected. When the
transducer indicates that a band corresponding to the permitted
limits for the particular gear lever position has been entered (see
block P5 of FIG. 3) there is a 0.5 second time delay (see block P6
of FIG. 2) before the clutch is engaged. This delay is to allow for
the operator to fully complete the movement of the lever to the
extremity of its movement after entering the permitted band of
lever positions for the gear in question. This extremity of
movement of the lever is recorded (see block P7 of FIG. 3). After
the clutch is engaged (see block P8 of FIG. 3) the engine speed and
road speed pulses are counted and the ratio of their pulse rates
determined. By reference to a look-up table (written into
non-volatile memory of the control unit 36 during production) the
actual gear engaged can be determined from the count ratio (see
block P9 of FIG. 3). The actual gear determined from the count
ratio is checked against the preceeding push or pull signal from
the gear lever sensor 33. If a valid ratio is found together with
the appropriate push or pull signal the system ascribes a future
permissable band of lever positions for the selection of the gear
ratio in question (see block P10 of FIG. 3) and sounds the buzzer
(see block P11 of FIG. 3) to indicate to the operator that he
should shift to the next gear selection position so that the system
can repeat blocks P1 to P11 described above. In this manner all the
forward gear selection positions are calibrated one after each
other.
When all the forward gear selection positions have been calibrated
the system checks that the vehicle has exceeded a predetermined
road speed eg. 60 k.p.h (see block Q of FIG. 2) to ensure that the
calibration of the forward gear selection positions which has taken
place is not accidental but is representative of the movements of
the gear lever in a real driving situation.
After all the forward gears have been calibrated the next step in
the process is to calibrate the reverse gear selection position
(see block R of FIG. 2). Calibration of reverse is the same as each
of the forward gears except that the speed correlation step (block
P9 in the forward sequence) is omitted thus the calibration can be
done with the vehicle stationary. The reverse calibration routine
thus including steps R1 to R8 and R10 corresponding to steps P1 to
P8, P10 and P11 described above.
When all the forward gear positions and the reverse gear position
have been calibrated the system checks that it has ascribed
permissable future gear lever ranges for each forward ratio and for
reverse (see block S in FIG. 2). This is shown diagrammatically in
FIG. 4 in which the gear lever selection gate for a five speed
gearbox is shown and each ratio has a permissable selection range
of positions (eg. ratio 1 has range a, ratio 2 has range b, ratio 3
has range c, ratio 4 has range d, ratio 5 has range e and reverse
has range r). These ranges are located as appropriate for the gear
in question on the appropriate side of the neutral permissable
range f.
If valid bands have been determined and saved for all the forward
gears and for reverse and a flag has been set confirming that the
vehicle speed has exceeded the predetermined road speed, (60 kph),
the buzzer is sounded (see block T of FIG. 2) to indicate the
completion of the entire calibration routine. Following which the
system can be keyed-off (see block U of FIG. 2).
As is evident from the above, the calibration routine proceeds
largely automatically with the operator being advised periodically
when he is required to carry out an action. For example, after the
sounding of the first buzzer the operator knows that he must fully
depress the accelerator for calibration of the foot-on throttle
position and the sounding of the second buzzer indicates to the
operator that the calibration of the foot-on throttle position is
complete and the calibration of the forward gear positions has
commenced and that he is therefore required to shift to each
forward gear position in turn with the buzzer sounding at the
completion of the calibration of each gear position. After the
final checking step S of the routine a final buzzer also sounds to
advise the operator that the full calibration routine has been
completed.
It is the above advising of the operators by the sounding of the
buzzer which signifies the necessary interaction between the
operator and the system and makes the control system of the present
invention so easy and fast to calibrate.
Also the manner in which the system ensures compatability between
gear selector lever loading signal and the gear ratio determined
from the engine speed and vehicle speed ratio correlation, during
the calibration of the forward gear selection positions, is seen as
an important feature of the present invention.
Alternatively, if deemed desired, the operator may be guided
through the calibration routine either by a written prompt sheet
through which he works systematically or by an electronic
diagnostic unit which is plugged into the control unit 36 and which
displays, at the appropriate moment in the calibration, an
indication to the operator as to the current stage of calibration
which is in progress and any actions which are required of him. As
a further alternative in a production line situation the operator
may be advised as to the current stage of the calibration and as to
any actions which are required of him by an overhead electronic
display which is connected with the control unit 36.
The calibrations which are determined during the above described
end of production line situation may need to be repeated (in part)
when replacement parts are fitted. Individual calibrations may be
carried out but require the use of the diagnostic facility and
prescribed procedures to alter the individual calibrations.
* * * * *